1. The Field of the Invention
The present invention relates to roadway sensors and, more particularly, to configuring intersection detection zones.
2. The Relevant Technology
The use of traffic sensors for the actuation of traffic signal lights located at the intersection of roadways is quite common. Generally, such traffic sensors can provide input used to properly actuate traffic control devices in response to the detection or lack of detection of vehicles. For example, traffic sensors can enable a traffic control device to skip unnecessary signal phases, such as, for example, skipping a left hand turn phase when no vehicles are detected in a corresponding left hand turn lane. Traffic sensors can also enable a traffic signal to increase green light duration for major arterials by signaling the green light in the minor cross streets (and thus a red light for a major arterial) only when vehicles are detected on a cross street. Thus, traffic sensors assist in properly actuating a signalized intersection to improve traffic flow.
In addition to the actuation of signalized intersections of roadways for automobile traffic, traffic sensors are also used for the actuation of intersections of a roadway for automobile traffic with other thoroughfares such as pedestrian paths or railways. In this specification and in the following claims, the term roadway intersection means the intersection of two or more roadways for automobile traffic including the approaches to the intersection or the intersection of one or more roadways for automobile traffic with one or more thoroughfares for other traffic, including the approaches to the intersection.
Unfortunately, the cost of traffic sensors and cost of corresponding installation can be relatively high. Thus, traffic sensors and related costs can become a significant expenditure for municipalities. The high installation costs arise at least in part from the need to install sensors for every approach to an intersection and from the time required to configure the traffic sensors.
Typically, traffic signal lights have been actuated using inductive loop detectors embedded in the roadway. Inductive loop detectors are very expensive to install since lane closures are necessary. The high cost is compounded, especially for multi-lane multi-zone roadways, since a separate inductive loop detector is required for each detection zone. Furthermore, inductive loop detector technology is often unreliable and inductive loop detectors require a great deal of calibration. Configuration time for these sensors is significant since the loops must be manually tuned and physically wired into the traffic controller in the proper configuration. Thus, detection zones that are implemented by inductive loops must be manually configured by the physical placement of the loop in the roadway and the physical wiring of the loop detector output to the traffic controller.
Video detectors have been gaining popularity for traffic signal light actuation. To facilitate traffic signal light actuation, a video camera is placed high above a signal arm such that the video camera's view covers one approach to the intersection. The video signal from the camera is digitally processed to create detection indicators when a vehicle is located in the configured zones. Since a dedicated mounting arm is often necessary and one camera per approach is required, the installation of a video detector system can also be expensive and time consuming. Furthermore, a time consuming manual configuration is required to configure the detection zones and associate them with the proper traffic signal phases. Even if a traffic governing agency has a set of guidelines that dictate the desired locations and functions of the detection zones, these zones must be manually entered into the video detector configuration.
Microwave detectors have also been used in intersections to provide detection coverage over limited areas. However, similar to video detectors, one unit per approach is required and manual configuration is needed to ensure that the detection zones are configured properly for each sensor. Furthermore, the detection indicator output from each sensor must be manually wired to the proper traffic controller input that corresponds to the correct signal phase. Acoustic sensors have also been used in intersections to cover limited detection zones. These sensors also require one unit per approach and must be manually pointed and configured to achieve detections in the desired zone.
Therefore systems, methods, and computer program products that facilitate automated configuration of detection zones and automated association of detection zones with traffic signal phases would be advantageous.